US researchers have hit upon a rather inexpensive, dependable and reversible male contraceptive from zapping testicles with ultrasound. This method can reduce sperm count.
Scientists from the University of North Carolina School of Medicine, who conducted experiments on male rats, issued their findings on Saturday in the journal Reproductive Biology and Endocrinology.
They said they were convinced that the method, if studied further, could be used on humans.
The best results were seen using two ultrasound sessions of 15 minutes, two days apart.
Saline was used to provide conductivity between the ultrasound transducer and the skin, and the testes were warmed to 37 degrees Celsius (almost 99 degrees Fahrenheit), the study noted.
The procedure reduced the sperm count to zero, the researchers said.
Fertile men in normal conditions have more than 39 million sperm when they ejaculate.
The World Health Organization has defined low sperm concentration as less than 15 million sperm per milliliter.
"Unlike humans, rats remain fertile even with extremely low sperm counts," Tsuruta said. "However, our non-invasive ultrasound treatment reduced sperm reserves in rats far below levels normally seen in fertile men."
He said that further studies will be required to determine how long the contraceptive effect lasts and if it is safe to use multiple times.